Quiz: Do you know how fluorescent lights work?

Let there be fluorescent light! Fluorescent lights are found everywhere, but do you know how they work? Those white tubes are more efficient than incandescent bulbs and don't get as hot. Take our quiz to see how much you know about the science inside these fluorescent lamps.

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Question 1 of 20

Light energy is made up of small particlelike packets that have __________.

mass and momentum but no energy

mass and energy but no momentum

energy and momentum but no mass

Light is a form of energy that is released by an atom. It consists of many small particlelike packets that have energy and momentum but no mass.

Question 2 of 20

A light particle that has energy is called what?

proton

photon

The most basic units of light are photons, which are released from atoms when their electrons become excited.

neutron

Question 3 of 20

When does a photon get released from an atom?

when an electron jumps to a higher energy level

when a proton moves closer to the nucleus

when an electron falls back to its original energy level

An excited electron holds its position for just a fraction of a second, then is drawn back toward the nucleus to its original orbit. As it returns to its original orbit, the electron releases extra energy in the form of a photon.

Question 4 of 20

What is the main difference between the different types of light bulbs?

the process for exciting atoms

In an ordinary incandescent light bulb, atoms are excited by heat. In a light stick, atoms are excited by a chemical reaction. Fluorescent lights have a much more complex system for exciting atoms.

the method of generating electricity

the color of the light emitted

Question 5 of 20

Which metal is contained in the sealed glass tube of a fluorescent light?

mercury

The sealed tube contains a tiny bit of mercury and an inert gas, commonly argon.

gold

copper

Question 6 of 20

What happens when a fluorescent lamp is turned on?

Electric current stops flowing to the electrodes.

The mercury heats up until it glows.

Electrons move through the gas from one electrode to the other.

When you turn on a fluorescent lamp, the current flows through the electrodes, which starts the movement of electrons from one end of the tube to the other.

The electrons in mercury atoms mostly release photons in the ultraviolet wavelength range. Human eyes cannot see ultraviolet photons, so they must be converted to visible light.

infrared

Question 8 of 20

Ultraviolet light is converted to visible light by what part of the fluorescent lamp?

a series of concave lenses

the powder on the inside of the sealed tube

The inner part of the sealed tube contains a phosphor powder coating. Phosphors emit light in the visible spectrum when they are exposed to ultraviolet light energy.

the white glass that the sealed tube is made from

Question 9 of 20

Why are fluorescent bulbs more energy-efficient than incandescent bulbs?

They are not as bright.

They use a lower voltage.

They emit less heat.

Incandescent light bulbs emit quite a bit of ultraviolet light, which is not converted to visible light, and they also emit more heat than fluorescent lamps, losing more energy in the process.

Question 10 of 20

Fluorescent lamps are how many times more efficient than incandescent lamps?

two

five

Although a typical fluorescent lamp is four to six times more efficient than an incandescent lamp, most people still use incandescent lights because they emit a "warmer" light.

nine

Question 11 of 20

What are ions?

something used to get the wrinkles out of your clothes

a type of electron with a positive charge

charged atoms that have gained or lost an electron

Ions are atoms that have lost or gained an electron. These charged atoms are drawn to oppositely charged areas, just like electrons.

Question 12 of 20

A fluorescent lamp needs what two things to send a current through the gas in the tube?

free electrons/ions and voltage

In a gas, an electrical charge is carried by free electrons or ions when there is a difference in charge between the two ends of the tube, i.e. voltage.

phosphor powder and proton pump

high current and an inert gas

Question 13 of 20

Which of these is a gas discharge lamp, which releases colored visible light when stimulated by ions and electrons?

Lava Lamp

incandescent lamp

neon lamp

Neon lights are gas discharge lamps that release colored visible light. Many street lights use a similar system with different gases.

Question 14 of 20

What happens inside a fluorescent lamp when it's turned on?

The light flickers until it warms up.

The lamp creates many free electrons to travel across the tube.

There are few ions and free electrons in a gas, so the first thing a fluorescent lamp needs to do is release many new free electrons from both electrodes.

The electrodes make ions hot to excite the mercury.

Question 15 of 20

What is inside the casing of a conventional fluorescent starter switch?

a small cylinder containing thousands of free electrons

a small bulb that creates free electrons when turned on

The conventional starter switch has a small gas discharge bulb, which boils off electrons from a metal surface and sends them into the main tube and ionizes the gas inside.

a fuse to control the voltage of current entering the tube

Question 16 of 20

What is the problem with the older conventional fluorescent starter switches?

They take a few seconds to light up the main tube.

Older fluorescent lamps take a few seconds to light up because the conventional starter switches take a few seconds to create enough ionizing gas for the main tube to start glowing.

They often need replacing every few months.

They don't allow dimming of the light for that "perfect" ambience.

Question 17 of 20

Instant-start fluorescent lamps apply a very high initial voltage to the electrodes, which creates a _________.

corolla discharge

corona discharge

A high initial voltage across the electrodes causes an excess of electrons on the electrode, with some electrons moving into the gas of the tube. This process, known as a corona discharge, ionizes the gas and sets off the electrical arc that lights the tube.

chroma discharge

Question 18 of 20

In terms of conducting electricity, what is a major difference between solids and gases?

Solids have no resistance to increases in current strength.

In gas discharge circuits, the flow of current causes the resistance to decrease.

In a gas discharge circuit, such as a fluorescent lamp, electric current causes resistance to decrease. This is because as more electrons and ions flow through a particular area, they bump into more atoms, which frees up electrons and creates more charged particles.

Gases don't conduct electricity.

Question 19 of 20

What part of a fluorescent light prevents an uncontrolled current from blowing out various electrical parts?

governor

starter switch

ballast

The simplest sort of ballast, a magnetic ballast, works like an inductor. It consists of a wire coil in a circuit, wound around a piece of metal, that works by opposing a change in the current flowing through it.

Question 20 of 20

Which of these is NOT caused by magnetic ballasts?

a noticeable flicker of the light

a bright glaring light

Magnetic ballasts limit the electrical current at a low cycle rate, which can cause the light to flicker and also results in the humming sound that you might associate with older fluorescent lamps.